System of space discharge tubes



Aug. 9, .1932. M. CLEMENT 53 53 SYSTEM OF SPACE DISCHARGE TUBES Filed June 50, 1924 v Ja e/fox Zen f5 MK/emenf by 4/7 Patented Aug. 9, 1932 units u STA-IE3 PATENT Free? LEWIs M. CLEMENT, or MOUNTAIN. LAKES, NEW JEEsEiAs'sIeNon TO wEsrEEN ELECTRIC. COMPANY, INCORPORATED, on NEW' roux," N.'.Y., AVGORPORIATIOIT OF.

NEW YORK SYSTEM or srAoE nIsoHAneEi TUBES Applicationzfiledlune so, 1924. seriarne. 723,147;

This inventionrelates to systems of'space discharge tubes and more particularly: to. radio transmitting.systemshaving means for 1 maintaining suitableaverage potentials upion 5 certain electrodes of space discharge: tubes included therein. 1

It has. been customary heretofore'to. utilize the. energy ofcurrent flowing in the space path. of: space discharge tubes for supplying m suitable polarizing potentialsto tube con v trol electrodes. Oneway in whichi thisresult has been accomplished has. beenv to in: elude a resistance-in. av path: common to the output and 1 input. circuits; of the space dis:

5 charge tubes in" such manner. thatiwhen our 4 rent flows therein a voltage willbeimpress'ed upon the. tube control electrodes by 'virtue'of the drop of potential along the resistance; An advantage of such. arrangement ie: the elimination of expensive and bulky? appara tus such as batteries or condensers whichiare ordinarily used to securethe proper control electrode potentials. A seriousdisadvanta'ge, however, which. results fromi such arrange ments,as heretofore used, is thatfwhen' a nega-v tlve potential is applied'to the. tube'contro'l electrodes by the drop OflPOtGlltldliIli there sistance, a condition favorable tocyclic'block ing and unblocking of the tubes is created;

It is an object of the invention'to stabilize systems of space dischargetubes.

ltis another objectv tov provide me'ansTfor maintaining suitable average potentialsiupon the control electrodes of space discharge tubes. 7 4

A further object is to preventib'locking and unblockingof the tubes in space discharge tube systems. in which. the control electrodes of the tubes are polarized by means o'fthe drop in potential. alongi'a resistance.

A feature of the invention relatesto means for maintaining a continuousfiow ofIcurrent through resistance.commontothe inputand output circuits of space dischargetubestor increasing the stability of the system.

In general, the invention may include'a resistance connected in common to theinput and output circuits of space-discharge-tubes which may form a part, forfexample of. a

59 radio trasmitting. system; A sourceaof space current: is connected inseriesawithlthe; resistance; andla shunt path. about the resistance and the-L space current source: is provi'dedi-for maintaining; a'. continuous flow of: current through the resistance: This" path. may ine elude another resistance: adjustedsto a su it v able :VflllllflifOI. maintaining. the proper: flow of current. a

In the drawing, a radio; transmittingrsys; tem. is illustrated. which embodiess the in; ventiom I V 1 The: radio transmitting circuit shown in the drawingtincludes; an. antenna. 101 electrostatically'coupled to a space dischargetube power. amplifiercQOsupplied with oscillations g from a: high frequency. oscillator 30. and" arrangedztobe controlled by a spaceidischa-rge tube powerwmodulator .40 supplied with low frequency waves from a-low frequency'oscile lator-50.v The system isxarrangedutoibecone h. trolled by a 1 source. of signals. represented by a telegraph key-51. The-antenna 10is. connected to ground in series with an: adjustable; loading: coilv 1 1-, variable. condenser 12, and high frequency ammeterf 13L: Condenser? 12 is: providedito couple theantennar circuit to tuned circuit: 14: including a portion ofthe variable. induc tance"15 and theicondenser'lti. This'tuned circuit is included inthe high frequency-output circuitioi' amplifier 20. which includes: the space discharge tube 21. This outp'utcircuit may be traced as follows: from the plate of. tube 21, choke. coil' 22, blocking; condenser 23, resonant circuit-14, choke coil:24.-to ground through condensers 25 tothe filamentzoftube 21. Thepurposeof the choke coil 24 is to. pro+ vide a path of suitable impedance to highfre' quency wavesfrom. the antenna. to ground whenthexswitch l7 'is thrown to its-left: hand contactto connect therant'enna to a counter p'oise- 18 instead of. to. ground. The. tube 2:1 hasaninputcircuitconnected to its control electrode; and cathode. which may be traced from. the control electrode through resistance 26, choke coil 31, resistance 32, ammeter same the intermediate tap of resistance 33' through the left hand portion or resistance 33 to ground: and from ground through: secondary winding of transformer: 45, resistances.86.; to 1 and also to balance the circuit.

The portion of the resistance 33 included.

in this input circuit is also included in a space current circuit of tube 21 connected to its anode and cathode. This circuit may be traced from the plate of tube 21, choke coil 22, choke coil 41, ammeter 42, low frequency choke coil 43, generator 44, resistance 33 to ground, and thence to the cathode of tube 21 via the path traced above. The generator 44 is shunted by a condenser 73 for reducing ripples in the space current by providing a lovi impedance path therefor. I The input circuit of amplifier is directly connected to the input circuit of space discharge tube 34 of oscillator 30. The inputcircuit of tube 34 may be traced from its cont-r01 electrode through choke coil 31, resistance-32, annneter 36, intermediate tap on resistance 33 to ground, thence to secondary winding of transformer 45, resistances 88 to the cathode of the tube. Condensers 64 and resistances 88 are provided at this tube for the same purposeas the corresponding elements at tube 21.

- The portion ofthe resistance33 included in the input circuit of tube 34 is also included in its'space current circuit. The space current circuit of tube 34 maybe traced from. its anode through choke coil 35, inductance 38, ammeter 52, choke coil 53, resistance 54, gen- .erator 44, resistance 33 to ground and thence to the midpoint on the secondary winding of transformer 45, resistance 88, and the cathode of tube 34. The high frequency output cir cuit of tube 34 includes its anode. high frequency choke coil 35, resonant circuit 37 to ground, and thence through condensers64 to the cathode of tube 34. The resonant circuit 37 includes a portion of the inductance 38 shunted by condensers 39 and 48. An ammeter 49 is connected between the condensers 39 and 48. Connection to ground is made between the ammeter 49 and the condenser 48. A blocking condenser 90 is provided to prevent direct current from the space path of tube 34 from flowing in the grid circuit of the tube. I

The output circuit of tube 34 is coupled to its input circuit by the inductance 38, whereby energy is fed from the output circuit to the input circuit for the purpose of generating sustained oscillations. These oscillations are supplied from theinput circuit of tube 34 to the input circuit of'tube 21 of amplifier 20. I V

The output circuit of the amplifier tube 21 is coupled to the alterating current output 63 circuit of modulator tube 55. Thelatter may I be traced from the anode of tube 55 through choke coil 56, ammeter 57, ammeter 42, bypass condenser 58 to ground, thence to condensers 25 and to the cathode of tube 55. The space current circuit of tube 55 may be traced from the anode of this tube through choke coil 56, ammeter 57, low, frequency choke coil 43, generator 44, resistance 33, to ground at midpoint of secondary winding of transformer 45, resistances 87 to the cathode of the tube. The input circuit of tube 55 is connected to its control electrode and cathode and extendsv from the control electrode through resistance 59, shunted by the secondary winding of transformer 60, resistance 33, shunted by condenser 61 to ground, and thence to the mid-point of the secondary of transformer 45 and to the cathode of the tube.

The low frequency oscillator 50 comprises the three-electrode space discharge tube 62 having an input circuitconnected between its control electrode and cathode which includes one winding of transformer 63, ground, secondary Winding of transformer 45, and switch 100. The alternating current output circuit of this tube is connected to its anode and cathode, and includes condenser 65, resistance '66, resistance 67, ground, secondary windingv of transformer 45, and switch 100. A feed-back circuit isconnectedto the anode and cathode and includes condenser 65, ad-

justable resistance 68, primary winding of transformer 63 shunted by condenser 69, ground, secondary winding of transformer 45, and switch. 100. This feed-back circuit is arranged'to-supply energy to the input circuit'by virtue of the coupling between the windings of transformer 63, whereby sustained oscillations are generated. The frequency ofthese oscillations is determined by the constants of the condenser 69 and the windingsof transformer 63 in shunt thereto.

The spacecurrent is supplied to tube 62 over a path connected to its anode and cathode which includes low frequency choke coil 7 O, resistance 71, generator 44, and resistance 33. The output circuit of tube 62 is connected in energy transfer relation to the inputcircuit of tube 55 .by a line connected to the terminals of resistance 67 which includes filter 74 or 75, switches 7 6 and 77 and the primary winding of transformer 60. Either one of filters 74 or. 75 may be included inthis circuit by actuating switches 76 and 77.

For controlling the operation of the system, a telegraph key 51, shunted by a series arrangementof resistance 78 and condenser 79, has its contact and lever connected to the grounded terminal and the midpoint of resistance 33, respectively. If desired, the key 51 may be replaced by the contacts of a relay arranged to be operated by a switch at a distant point. The space discharge tube system or radio transmitter could then be remotely controlled.

Current for heating all of the cathodes of tions are likewise supplied from the outout the various tubes'is suppliedfrom a common source-represented as an alternating current generator which is connected to the primary winding of the transformer 45. The secondary winding of this transformer is tapped at variouspoints by leads 46,82, and

83 for supplying current to the cathodes of tubes 34, 62, and 55 and 21, respectively. The

midpoint of the'secondary winding-of transformer 81 isconnectedto ground. This syscircuit of tube 62 through the filter 74 or 7 5, as the case may be, and transformer 60 to the input circuitof tube 55 when switch is closed. Oscillator 50 is preferably adjusted to generate the oscillations within the audible range of frequencies.

Filters 74 and 75 are designed to prevent the transmission of waves of harmonic frequencies which may be generated by the oscillator 50. Filter 74, for example, may be a low pass filter designed to pass currents of frequencies below 600 cycles per second only, whereas filter 75 may be designed to pass currents of frequencies-below 1200 cycles per second.

By virtue of the connection between'the out-put circuits of tubes 55 and 21, the high frequency waves produced in the output circuit of tube 21 are modulated in accordance with the low frequency waves in the output circuit of tube 55. These modulated waves are transmitted through the coupling afford ed by condensers 12 and 23 toth-e antenna 10 and are'iadiated therefrom. As a means-of signaling, the telegraph key 51 is arranged when operated to short circuit a portion of the resistance 33-sufficient to reducethe negative potential upon the controlelectrodes of tubes 21, 34, and 55, whereby they are placed in operative condition. Consequently, during the time that key5'1 is closed, the high frequency waves from oscillator 30 modulated in accordance with low frequency waves from oscillator 50 are transmitted from antenna 10. On the other hand, during the time that key 51 is open, resistance 33 impresses a negative potential upon the control electrodes of tubes 34, 21, and 55 sufiicient to greatly reduce or stopthe flow of space cur- .rent therein and consequently suflicient to prevent thetransmission of waves therefrom. Oscillator 50 remains in operative-condition at all-times so longasswitch 100-is-.closed.

mittedvfrom the antenna when key 51is oper-- trodes which has theefiect of reducing the .flow of space current. to reduce the potential applied to the control trodes of these tubes. provided to prevent-the loss of power at the In operating the system as a continuous wave system, therswitc-h 100;is opened; The oscillator 50 is thereby rendered inoperative and only. high frequency waves are transated.

A resistance 85 is connected in shunt'to the generator 44 and resistance 33 for the purpose of maintaining, a continuous flow of current throughresistance 33, as a means of preventing blocking and. unblocking of the tubes of the system whenkey 51 is open.

This tendency of thetubes to-block and unblock is'caused by the fact that an increase of space current causes an increase-in the drop of potential along the portion of resistance 33 included in the tube input circuits. 'ThlS increased potential increases the negative polarization of the tube control elec- This in turn tends electrodes which results in an increased" flow of space current. Resistance 85 is provided to maintain at all times theproper flow of current through resistance 33.

Various ammeters are included'in-the circuit for indicating the flow of current there in. Ammeten 13 is provided to indicate the antenna current. in the resonant circuit 14 to indicate the flow of current in this circuit. Likewise, am-

ineters 42, 57, 52, 36, and 49 are provided for indicating the flow of current in the particular circuits with which theyare associated. I

Choke coils 35, 22, and 56 are provided in the leads .connected to the anodes of tubes 34, 21, and 55 for preventing the generation of parasitic oscillations or singing. Resistance 26 isincluded in the lead connecting the control electrodes of tubes 21and 34 for, supplementary 'tochoke coil. 22, preventing the generation of parasitic oscillations or singing in the amplifier tube 21.

Condenser 7 3, connected in shunt to generator 44, is provided to supply a low impedance path for current variations such,

for example, as commutator ripples. Likewise, condenser 61 connected in shunt to resistance 33- provides a low impedance path for variable components of current as a means for preventing th se variations from being transmitted as variations of potential to the control electrodesof tubes 21, 34, and

55. Rcsistances 86, 87, and 88 and condensers 25, 25, and 64 are provided in the filament heating circuits of tubes 21, 55,'and 34 for balancing these circuits to prevent the intro duction'of current variations corresponding to the variations of source 80 into the circuits connected'to the anodes and control elec- The condenser 58 is high frequencies in the ehokecoil 43. This i Ammeter 13 is included condenser provides a low impedance path to ground in shunt to the choke coil 4:3,generator 44:, and resistance 33. 1

Adjustable resistance 59 enables low frequency waves of the proper voltage to be impressed upon the input circuit of tube 55.

Condenser 65 in the circuit of low frequency oscillator 50 is provided to prevent the passage of direct current'from source 44 through the alternating current output circuit of the tube. Adjustable resistance 68 is provided to enable the energy fed back from the output circuit to the input circuit to be adjusted to the proper value for producing sustained oscillations.

The right hand portion of resistance 33 is provided to supply a suitable polarized potential to the control electrode of tube 55 during the time when key 51 is closed.

Resistance 67 is a coupling resistance designed to provide the proper potential for operating the modulator tube 55. Resistance 66 which is in series with resistance 67 cooperates with it in producing this result.

Although this invention has been illustrated and described in connection with a particular embodiment of the invention, it is intended to be limited only as indicated by the scope of the appended claims.

What is claimedis:

1. In a space discharge device system, a space discharge device comprising an anode, a cathode, and a control electrode, means for maintaining suitable average potential upon the control electrode of said device comprising a source of space current, a direct current path connected to the terminals of said source and including said anode and cathode in series with a resistance, a connection to said control electrode from a point in said resistance, and a second direct current path including a constant resistance external to the space discharge device in shunt to a portion of the first named direct current path.

2. In a space discharge system, a space discharge device having a plurality of electrodes including a control electrode, an anode, and an electron emitting cathode, means for maintaining suitable average potentials between the control electrode and cathode of said device which comprises a direct current source connected to said anode, a resistance in series with said source and cathode, a path between said control electrode and said cathode, which also includes said resistance, and a direct current path including a constant resistance. external to the space discharge device connected across theterminals of the series path including said source and said first named resistance.

3. In a space discharge device system, in-

cluding a plurality of space discharge devices each having an electron emitting cathode, an anode and an impedance controlling electrode, means for applying polarizing potentials to said control electrodes comprising a resistance and a source of current included in a path between said anodes and said cathodes, a path which also includes said resistance connected between said cathodes and said control electrodes and a resistance external to said space discharge devices connected to said first mentioned resistance and to the terminal of said source remote therefrom for maintaining a continuous flow of current through said first mentioned resistance.

l. In a radio transmitting system including a space discharge device having a control electrode, cathode and anode, means for applying suitable negative potentials to the control electrode of said device, comprising a resistance connected between the control electrode and cathode and included in series with a source of current, signaling means connectedto permit short-circuiting a portion of said resistance, and a direct current path in shunt to said resistance and said source.

- .5. In a radio transmitting systeniincluding a plurality of space discharge-devices,

means for applying to the control electrodes of certain of said devices a negative potential suflicient to block the flow of space current therethrough, means for preventing-automatic unblocking of said devices, and signaling means arranged to control the flow of space current in said tubes.

6. In a radio transmitting system, plurality of space discharge tubes each including a cathode, anode and control electrode, aresistance traversed by space current in said tubes, said resistance being connected to the control electrodes thereof, signaling means arranged to short circuit-a portion of said resistance, and means for maintaining a continuous flow of current through said resistance. V

7 In combination, a space discharge tube having a cathode and an anode and a vcontrolelectrode, an input circuit connected to the control electrode and cathode and an output circuit connected to the anode and cathode of said tube, a resistance included in both of said circuits, and'a source of. current included in said output circuit in series with said'resistance, signaling means arranged to short-circuit a portion of said resistance and a direct current path connected to said anode and cathode in parallel with said source'and said resistance.

8. In a radio transmitting system, an antenna, a space discharge tube amplifier having input and output circuits, coupled to said antenna, a space discharge tube modulator accordance with said signals, high frequency waves modulated by low frequency oscillations, said means including a resistance traversed by space current'from said tubes and means to maintain a continuous fiow of current through said resistance.

9. In a radio telegraph transmitting system, an antenna, a power amplifier and a power modulator coupled to said antenna, a high frequency oscillator supplying waves to said amplifier, a low frequency oscillator supplying waves to said modulator whereby high frequency waves modulated in accordance with low frequency waves may be supplied to said antenna, and means for controlling the transmission of waves from said system comprising an impedance, a source. of current connected to said impedance, a telegraph key arranged to short circuit a portion of said impedance, and a resistance in shunt to said impedance and said source.

10. In a radio telegraph system, a space discharge tube amplifier, an antenna coupled thereto, a space discharge tube oscillator for supplying oscillations to said amplifier and antenna and means for controlling the generation of oscillations by said oscillator comprising a resistance and a direct current generator in series, a path in shunt to said resistance and generator for maintaining a fiow of current through said resistance, and a key arranged to short circuit a portion of said resistance.

11. In a radio sending system, a radio frequency source, an amplifier controlled thereby, an audio frequency source operatively associated with said amplifier to exert an additional control thereon, and a keycontrolled means for impressing a blocking potential simultaneously on both sources.

12. A radio sending system comprising a source of radio frequency oscillations, a source of audio frequency oscillations, an amplifier controlled by said radio and audio requency sources and means for simultaneously applying'a blocking potential to both said sources.

13. In a radio sending system, a source of radio frequency oscillations, an amplifier controlled thereby, a source of audio frequency oscillations operatively associated with said amplifier to exert an additional control thereon, and key-controlled means for impressing a blocking potential on said amplifier and simultaneously on both sources.

14:. In a radio transmitting system, a source of radio frequency oscillations comprising a triode, an amplifier comprising a triode, a source of audio frequency oscillations comprising a triode, connections whereby said amplifier may be jointly controlled by said ,radio frequency source and said audio frequency source, a common source of plate potential for said triodes, and means whereby a blocking potential may be derived from said common source and applied simultaneously to the grids of said triodes.

15. In a radio transmitting system, a source of radio frequency oscillations comprising a triode, an amplifier comprising a triode, an audio frequency source comprising a triode, connections whereby said amplifier may be jointly controlled by said radio frequency and said audio frequency sources, a common source of plate potential for. said triodes, means for deriving a negative potential from said common source, and a keying device for controlling the application of said negative potential to the grids of said triodes.

16. In a radio transmitting system, a source of radio frequency oscillations comprising a triode, an amplifier comprising a triode, a source of audio frequency oscillations comprising a triode, connections whereby said amplifier may be jointly controlled by said sources of radio and audio frequency oscillatlons, a common source of high potential for the plates of said triodes, resistance connected inshunt to said source, connections whereby said resistance serves to negatively bias the grids of said triodes with respect to their cathodes, and means for establishing a shunt around at least a portion of the resistance which supplies said negative bias.

17 In a radio transmitting system,a source of carrier oscillations comprising a triode, an amplifier comprising a triode, an audio frequency source comprising a triode, a common source of plate potential for said triodes, means for deriving a negative potential from said common source, and additional means for applying said negative potential at will to the grids of said triodes.

18. In a high frequency signaling system employing a master oscillator and power amplifier for oscillations produced by said oscillator, said oscillator and said amplifier being of the vacuum tube type, a source of potentialfor the anodes of said oscillator and said amplifier, a permanent connection between the grids of said oscillator and said amplifier and the negative side of said source of potential, a connection between the oathodes of said oscillator and said amplifier and the negative side of said source of potential, means for controlling the operation of said oscillator and said amplifier comprising a contact making key inserted in said last mentioned connection, one side of said key being connected to the negative side of said source of potential and to said grids, and the other side of said key being connected to the oathode, and means associated therewith and adapted to maintain a definite potential on said grids and across said key when said key is open.

In Witness whereof, I hereunto subscribe my name this 25th day of June, A. D. 1924.

LEWIS M. CLEMENT. 

